Gigabit-capable Passive Optical Networks (GPON), specified by ITU-T Recommendations G.984.1, G.984.2, G.984.3 and G.984.4, are widely adopted by network operators across the world as the broadband access network of choice. With bit rates of 2.488 Gbps in the downstream and 1.244 Gbps in the upstream direction, GPON provides high enough bandwidth per user to enable efficient simultaneous delivery of services such as voice, internet access, broadcast television, video on-demand (VOD) and high definition television (HDTV) etc. However, with the emergence of new services delivered over access networks, the demand for bandwidth is anticipated to grow beyond the capacity of GPON. To meet this demand, standardization of the Next-generation of GPON (NGPON), featuring higher bit rates, is being considered. In the early discussions about NGPON, network operators have emphasized the need for compatibility of NGPON and GPON, that would warrant co-existence of these two systems on the same physical PON, without disrupting each others operation. This approach would be cost-effective for the network operators because it would allow phased upgrade of the GPON infrastructure, without the need to upgrade customer premises equipment (CPE) for those customers who prefer to stay subscribed to the old, less expensive GPON service.
To achieve this goal, compatibility of NGPON and GPON must be achieved at both the physical (PHY) and media access control (MAC) layer. A system and method for solving the physical layer is disclosed in the Applicant's co-pending application Ser. No. 12/074,692, the entire contents of which are explicitly incorporated herein by cross reference.
What is required is a system and method for providing compatibility of NGPON and GPON at the MAC layer.